1. Field of the Invention
The invention relates to a system and a method for continuously manufacturing a liquid crystal display device by a process including peeling off a sheet piece of a polarizing film from a carrier film and bonding the sheet piece to a liquid crystal panel with a pressure-sensitive adhesive interposed therebetween.
2. Description of the Related Art
A known method for continuously manufacturing a liquid crystal display device includes providing a carrier film on which a sheet piece of a polarizing film is formed with a pressure-sensitive adhesive interposed therebetween, peeling off the sheet piece of the polarizing film together with the pressure-sensitive adhesive from the carrier film by inwardly folding back the carrier film at the front end of peeling means, and bonding the sheet piece of the polarizing film, which is peeled off, to a liquid crystal panel with the pressure-sensitive adhesive interposed therebetween by bonding means, while feeding the liquid crystal panel (see Japanese Patent Application Laid-Open (JP-A) No. 2004-361741).
The system disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2004-361741 for continuously manufacturing a liquid crystal display device is required to continuously produce a liquid crystal display device at a velocity as high as possible. In the process of bonding the sheet piece to the liquid crystal panel (bonding process), therefore, the velocity V1 at which the carrier film is taken up and the bonding velocity V2 should preferably be set as equal as possible. In addition, the bonding process itself should preferably be performed at a velocity as high as possible (the bonding velocity V2 should preferably be set as high as possible). On the other hand, the interval between the bonding processes (for example, the time required to align the sheet piece) should be reduced. For this purpose, the take-up velocity V1 should preferably be reduced as much as possible before the carrier film is stopped so that the carrier film can be stopped with high accuracy.
It is therefore disclosed that the bonding process includes bonding a sheet piece to a liquid crystal panel at a high velocity, while keeping the carrier film take-up velocity V1 and the bonding velocity V2 are kept equal to each other (V1=V2) until an intermediate time during the bonding, then temporarily reducing the take-up velocity V1 and the bonding velocity V2, while keeping them equal to each other, and further making the carrier film take-up velocity V1 smaller than the bonding velocity V2 (Japanese Patent Application Laid-Open (JP-A) No. 2004-338408).    Prior art document: Japanese Patent Application Laid-Open (JP-A) No. 2004-361741 and Japanese Patent Application Laid-Open (JP-A) No. 2004-338408.
However, pressure-sensitive adhesive portions, which are formed on sheet pieces adjacent to each other with a score line therebetween, adhere to each other after the score line is formed. In such a case, when the velocities are controlled as described in Japanese Patent Application Laid-Open (JP-A) No. 2004-338408, namely, controlled in such a manner that V1<V2 is established when the next sheet piece following the sheet piece being bonded reaches the front end of peeling means (or when the rear end of the sheet piece being bonded reaches the front end of peeling means), the sheet piece being bonded is separated from the next sheet piece in such a state that the front end of the next sheet piece being fed together with the carrier film is slightly curled (slightly folded back) on the front end of the peeling means, so that air voids may be more likely to be formed due to adhesive lacking (loss of part of the pressure-sensitive adhesive) or adhesive deposit (deposition caused by chipping of part of the pressure-sensitive adhesive).